Behavioral and neurophysiological methods will be applied to study the mechanism of electrolocation in electric fish. Since electrolocation is based upon the evaluation of feedback from the animal's electric organ discharges it is most vulnerable to electrical noise, particularly to discharges of conspecifics. Behavioral and neuronal mechanisms which serve in the detection and enhancement of electric images in the presence of noisy backgrounds will be investigated. To elucidate problems of electric image processing, computer simulations and electrophysiological methods will be employed to study the nature of electric images and their "blurring" in the presence of electrical noise of given qualities and intensities. Of particular interest is the comparison of pulse- and wave-species, since their drastic differences in electric organ discharges suggest different mechanisms of electric image processing. Further differences are expected between African and South American representatives of pulse-and wave-types respectively which, in the course of their convergent evolution, may have found different solutions to the same problems. Electric fish are a superb model system to study different behavioral and neuronal solutions to fundamental problems such as feedback identification, signal detection and image recognition, for various reasons: Simplicity of electrical stimuli, easily accessible receptors distributed on the animal's body surface, and identifiable behavioral responses which can function even under harsh conditions necessary for electrophysiological experimentation.